Mesh becomes flat when working with Fracture Modifier Branch. Is this a regular bug?
Hmm, this looks very odd indeed. Looks like something has been scaled to 0 in one direction accidently. The FM does apply the scaling when fracturing, though.(bullet cannot deal very well with scaled objects, imho).

But without the blend this is all just guessing. Could you share it here maybe, so I can take a look ?